That's weird, because I didn't get that much experience orbs as the "First Dragon" should give.
So that means I will only have 19 End Gateways maximum instead of 20?
So now, eh... The problem got fixed. I wanna continue on this: I just killed the Ender Dragon for the second time (first one in 1.10 and today in 1.10.1) I only have 1 End Gateway: new ones aren't generating...
It's because of the knockback: the arrow you shoot is slower than you. As this game involves real life physics sometimes, the speed you fly should be added to the base speed of the arrow. This also fixes why you shoot yourself while walking, riding a minecart or moving with another entity.
I tested while shooting sideways riding a minecart. A friend measured but I was just shooting straight. No forward speed. (First law of Newton!)
Please make Newton happy by adding this mechanic to the game. (The third law could be fun as well, like breaking softer blocks while flying straight into it with Elytra.)